/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */
package org.springframework.security.web.context.request.async;

import java.util.concurrent.Callable;

import org.springframework.security.core.context.SecurityContext;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.util.Assert;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.async.CallableProcessingInterceptor;
import org.springframework.web.context.request.async.CallableProcessingInterceptorAdapter;

/**
 * <p>
 * Allows for integration with Spring MVC's {@link Callable} support.
 * </p>
 * <p>
 * A {@link CallableProcessingInterceptor} that establishes the injected {@link SecurityContext} on the
 * {@link SecurityContextHolder} when {@link #preProcess(NativeWebRequest, Callable)} is invoked. It also clear out the
 * {@link SecurityContextHolder} by invoking {@link SecurityContextHolder#clearContext()} in the
 * {@link #postProcess(NativeWebRequest, Callable, Object)} method.
 * </p>
 *
 * @author Rob Winch
 * @since 3.2
 */
public final class SecurityContextCallableProcessingInterceptor extends CallableProcessingInterceptorAdapter {
    private SecurityContext securityContext;

    /**
     * Create a new {@link SecurityContextCallableProcessingInterceptor} that uses the {@link SecurityContext} from the
     * {@link SecurityContextHolder} at the time {@link #beforeConcurrentHandling(NativeWebRequest, Callable)} is invoked.
     */
    public SecurityContextCallableProcessingInterceptor() {
    }

    /**
     * Creates a new {@link SecurityContextCallableProcessingInterceptor} with the specified {@link SecurityContext}.
     * @param securityContext the {@link SecurityContext} to set on the {@link SecurityContextHolder} in
     * {@link #preProcess(NativeWebRequest, Callable)}. Cannot be null.
     * @throws IllegalArgumentException if {@link SecurityContext} is null.
     */
    public SecurityContextCallableProcessingInterceptor(SecurityContext securityContext) {
        Assert.notNull(securityContext, "securityContext cannot be null");
        setSecurityContext(securityContext);
    }

    @Override
    public <T> void beforeConcurrentHandling(NativeWebRequest request, Callable<T> task) throws Exception {
        if(securityContext == null) {
            setSecurityContext(SecurityContextHolder.getContext());
        }
    }

    @Override
    public <T> void preProcess(NativeWebRequest request, Callable<T> task) throws Exception {
        SecurityContextHolder.setContext(securityContext);
    }

    @Override
    public <T> void postProcess(NativeWebRequest request, Callable<T> task, Object concurrentResult) throws Exception {
        SecurityContextHolder.clearContext();
    }

    private void setSecurityContext(SecurityContext securityContext) {
        this.securityContext = securityContext;
    }
}
